Tip #13. People picker selects "disabled" accounts

People Picker is a nice feature of SharePoint which allows search for a user/group when assigning permissions for example. But it has one issue - it selects the accounts and groups which are “disabled” by default. It's probably what you don't expect to be selected when you configure permissions, because it creates potential security breach

To remove "disabled" user/groups from the selection you need to apply LDAP filters via STSADM command